Greater Loss of Slow-Wave Sleep is Associated with Metabolic & Cognitive Problems in Boys

Background:Slow-wave sleep (SWS) predominates the first half of a night’s sleep. Characterized by high-amplitude, low-frequency, synchronized EEG activity, SWS is involved in memory consolidation, recovery after sleep deprivation, and is associated with reduced cortisol and proinflammatory cytokine production. The decline of SWS across the lifespan has been well-documented. Although SWS is thought to play a role in health and disease, no study to date has examined possible physical or neurocognitive consequences of this decline. The aim of this study was to longitudinally assess the effects of SWS loss from childhood to adolescence on cardiometabolic and neurocognitive outcomes in a large population-based sample. Methods:The Penn State Child Cohort is a representative general population sample of 700 children (aged 8.6 ± 1.7 years) of whom 421 (53.9% male) were followed up 8 years later during adolescence (aged 17.0± 2.3 years). At both time points, participants underwent a single 9-hour polysomnography recording. The change in SWS over time was calculated as the percentage of SWS at baseline minus that at follow-up. At follow-up, a dual-energy X-ray absorptiometry scan (to measure body fat), fasting morning blood draw (to assess insulin resistance), and neurocognitive testing were also conducted. A linear regression assessed the association of the change in SWS on various metabolic and neurocognitive outcomes at follow-up separately in males and females, adjusting for age, BMI percentile, race, and the time elapsed between laboratory visits. Results:In boys, a greater decline in SWS across adolescence was significantly associated with insulin resistance (B=0.17, p=0.01). A greater loss of SWS was also marginally associated with increased visceral fat area (B=0.09, p=0.09) and impaired vigilance (B= -0.15, p=0.06) in boys. No associations between SWS and any cardiometabolic or neurocognitive outcomes, however, were observed in girls (p=0.48-0.52). Conclusions: A greater loss in SWS from childhood to adolescence is associated with insulin resistance, increased visceral fat, and impaired vigilance in adolescent boys, but not girls. Future studies should examine how the decline of SWS is associated with gender differences in physical health and neurocognitive outcomes into young adulthood and middle age.